Electrical machine

ABSTRACT

The invention relates to an electrical machine, in particular to a motor or a generator, comprising at least a stator ( 30   a   , 30   b ), a plurality of winding teeth ( 32   a, b ) arranged on the circumference of the at least one stator ( 30   a, b ) with windings and the winding teeth comprising clearances ( 34   a, b ) therebetween, wherein all windings of each stator are connected in series. The electrical machine further comprises a rotor ( 1 ) and a plurality of permanent magnets ( 5 ) and/or rotor windings arranged at the circumference of the rotor ( 1 ), wherein the poles of the permanent magnets and/or rotor winding directions are radially aligned and alternating. Preferably, two stators ( 30   a, b ) are provided, which have an angular offset (α) to each other. Further, a control circuit for an electrical machine comprising at least one phase winding is provided, the control circuit comprising four power switches per corresponding phase winding for the control of the electrical machine.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

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INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable

BACKGROUND OF THE INVENTION

The invention relates to a primarily brushless electrical machine whichin particular can be operated as a generator and/or synchronous motor.

BRIEF SUMMARY OF THE INVENTION

It is an object of the invention to provide an electrical machine withsimple construction with an especially high power/size ratio. It isfurther an object of the invention to provide a control circuit and agenerator arrangement particular useful when combined with such anelectrical machine.

An electrical machine comprises at least one stator. Every statorcomprises a plurality of winding teeth with windings wherein allwindings—at least magnetically seen—are connected in series. i.e., onesingle conducting wire is sufficient to wind all winding teeth of astator. ‘Winding’ on one of the winding teeth respectively stator teethmeans either a plurality of winding loops of a conducting wire which isfirstly winded around a winding tooth and then in a plurality of windingloops which are for example winded around the neighboring winding tooth.Or the ‘windings’ are composed of a plurality of loops which windsbetween the winding teeth. Particularly when the conducting wire of awinding tooth is passed to its neighboring winding tooth or the loopsare guided from winding tooth to winding tooth without skipping awinding tooth, this results in no ‘inactive’ portions of the windingwire, so that the use of the magnetic flow for actuation or for powergeneration is 100%.

A plurality of permanent magnets with alternating polarity poles or—inan embodiment—a plurality of winded rotor winding teeth with alternatingwinding direction is located at the rotor. Optionally the rotor windingteeth are combined with permanent magnets. Preferably the rotor windingteeth are connected in series—according to the serial connection at thewindings at every stator.

Preferably the rotor only comprises permanent magnets, so that only thecontacting of the winding teeth of one or more stators is required whichis provided by a fixed connection (rotation-free contacting).

In the electrical machine according to claim 3 the rotor teeth of arotor are provided with serial connected rotor tooth windings. Theserial winding of the rotor teeth corresponds to the winding of thestator teeth in claim 1, so that here a 100% use of the conducting wirefor generating the actuation power or for energy generation is providedas well.

Preferably the stator unit or the rotor unit are composed of at leasttwo parts. E.g. at least a first and second stator each comprising aplurality of winding teeth or at least a first and a second rotor eachcomprising a plurality of rotor winding teeth, wherein the winding teethrespectively the rotor winding teeth are arranged with angular offset toeach other. Embodiments comprising three or four stator or rotor unitsare also applicable quite well as regards the dimensions at high engineand/or generator power. Preferably the winding teeth or rotor windingteeth of the stators or rotors are arranged symmetrically in angularoffset to each other. When using the electrical machine as motor, theangular offset of the stators (rotors) to each other results in areduced starting torque and the running direction can be determined byapplying a voltage at the winding of the adequate stator (rotor). Whenusing the electrical machine as a generator, the difference between theminimum and maximum rectified voltage is the smaller the higher thenumber of the angular offset stators (rotors) is.

Under the aspect of manufacturing it is cost-saving to pre-produce thestator units or rotor units each as identical or almost identicalmodules and to assemble these modules for final manufacture of themotors and/or generators according to the desired stator or rotor(module) number.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Embodiments are described by the following figures, which show:

FIG. 1A a schematic, perspective view of a generator according to theinvention,

FIG. 1B a top view of the generator of FIG. 1A with windings,

FIG. 2A a simplified equivalent circuit of the generator of FIG. 1A,

FIG. 2B a stretched view of the stator and rotor of the generator ofFIG. 1A,

FIG. 3 an equivalent circuit of the generator of FIG. 1A in use as adirect current generator,

FIG. 4 a schematic view of the winding scheme of the stator of thegenerator shown in FIG. 1A according to a first embodiment,

FIG. 5 a schematic view of the winding of the stator of the generator ofFIG. 1 according to a second embodiment,

FIG. 6 the winding scheme of FIG. 5 in perspective view,

FIGS. 7A and 7B a top view and a perspective view of a stator for thegenerator of FIG. 1 in a second embodiment,

FIGS. 8 and 9 a front view and a perspective view of a generator ormotor with a dual stator,

FIG. 10A a schematic, stretched view of the dual stator of FIG. 9 withwinding,

FIG. 10B a schematic side view of the stator according to FIG. 10A,

FIG. 10C a time voltage and position diagram illustrating the magnetpositions and the applied voltage in motor operation,

FIG. 10D a side view according to FIG. 10B when using the stator of FIG.1A instead of the stator of FIG. 9,

FIG. 11 a block diagram of a motor unit when using the generator of FIG.9 as drive or actuation motor and generator,

FIG. 12 a block diagram of an embodiment of the motor unit in FIG. 11with a simplified rectifier construction,

FIG. 13 an enlarged partial view of FIG. 12,

FIG. 14 a time diagram of the generator voltage gripped and rectifiedfrom both stator windings, and

FIG. 15 another embodiment of the partial circuit of FIG. 13 with acontrol unit.

DETAILED DESCRIPTION OF THE INVENTION

The electrical machine described in the following is applicable asexternal rotor as well as internal rotor. The embodiments shown in thefigures represent an external rotor as twelve pole machine forsimplification. Preferably neodymium bars are used as permanent magnets.Dependent on the technical need other magnet material is applicable too.

The functional principle of the basic example of this machine is basedon the proportional sequence of rotor poles and stator poles which arearranged evenly at the circumference, respectively. In the normal casean even number of poles is used. The number of poles can also be quitehigh in order to reach higher frequencies or better rotationcharacteristics of the electrical machine. The potentially high numberof poles generates a correspondingly high frequency of the outputvoltage (generator). In combination with a bridge rectifier this enablesa very clean direct current using quite small filter capacitors withoutthe creation of high frequency distortions as it is the case withcollector generators.

Application as Generator (FIG. 1A-7)

By way of an example of a twelve pole generator FIGS. 1A and 1B show arotor 1 and FIG. 1A a non-winded stator 3 in a three-dimensional view.The rotor 1 comprises equally spaced permanent magnets 5 assembledalternating as north and south poles pointing to the axis. In this casethe stator 3 comprises the same number of teeth 7 as the rotor 1. Theteeth are also often called anchors, armatures or poles and the windingson them as anchor winding. Here twelve magnets 5 and twelve equallyspaced teeth 7 are used. The stator teeth 7 are alternatingly wound inleft and right turns with windings 11 which are all connected in series.The windings 11 shown in the cross section of FIG. 1B are winded in thisway to the individual teeth 7 as conventionally. I.e. in this case thewhole winding is formed at one tooth 7, before the winding is formed atthe next tooth completely.

The alternating arrangement of the stator poles 7 as well as the rotorpoles 5 in the same way is to be emphasized. This enables the serialconnection of all windings 11.

In each stator coil respectively winding 11 of a stator tooth 7 aninduction voltage is generated by the same number of magnet poles andstator poles or stator teeth during a rotation of the rotor 1 when thestator teeth pass over the rotor poles. However the windings have to bewinded on the stator teeth alternating inversely or have to be connectedaccordingly since on rotor 1 there are also alternatingly polarizedmagnet poles 5.

FIG. 2A shows the winding orientation of the twelve pole generator ofFIG. 1A of construction type in an uncoiled view as equivalent circuit.FIG. 2B shows schematically in an uncoiled view the sequence of themagnets 5 and opposite teeth 7 with alternating winding direction. Asdescribed before the rotor 1 is provided with alternating permanentmagnets. The stator 3 has the same number of teeth as the rotor. Thestator teeth are winded alternating left hand and right hand turns. Dueto the continuous change of the pole direction when rotating the rotor,the same voltage or current direction is induced in the windings of thestator by the winding of the teeth in alternating direction. Thewindings can therefore be all connected in series.

Therefore a common mode of the induction voltages of all stator windingsis the result. As shown in FIG. 2A the AC voltage U˜ is generated at ACvoltage terminal 12 as sum of all induction voltages of the twelvewindings. The frequency f of AC voltage U˜ created during the rotationis as follows:f=(number of stator poles)/2*rotor rotation speed with rotor rotationspeed in rotations/min/60 and f in Hz.

As shown in FIG. 3 by a downstream connected rectifier 13 it is possibleto create a direct current voltage U_(DC) at a direct current voltageterminal 17 from the AC voltage U˜, directly without additional devices.With an increasing number of poles, quite high frequencies can bereached, which results in very good smoothing just with relatively smallfilter 15 capacities.

Advantages of the previously described generator:

-   -   in this embodiment the generator is brushless (unless in a        further embodiment the rotor is provided with excitor windings        for a controlled (feed-back) operation);    -   the high starting frequency allows a good smoothing already at        low rotating speed and already with quite small capacitors        (direct current generator);    -   the winding is easy to wind and low cost;    -   by the simple construction it is ideal for simple applications,        for example a bicycle dynamo;    -   due to the very compact design it is very small and light;    -   apart from the feed wires the whole copper of the winding at the        stator tooth is active, it therefore has a very high efficiency;    -   this design just requires two wire ends per stator ring or        stator unit.        Winding in Alternating Direction:

As shown in FIGS. 4 and 5 the serial arrangement of the poles on thestator 3 enables in this embodiment a particular winding mode of theexcitor windings 11. Since a changing winding direction is required dueto the changing arrangement of rotor poles 7, always alike currentdirections coincide in a stator notch 9 between the teeth 7. Thisenables a new winding mode making separate connections between theparticular windings 11 from tooth 7 to tooth redundant. The windingdirection is alternating through the particular notches 9 or gaps, ringper ring over the whole stator 3 until the desired filling of the notch.Therefore all windings 11 are automatically connected in series. Herein,a substantial advantage is the lack of any inactive interconnectionbetween the pole windings, which considerably increases the efficiencyof this electrical machine. In addition, a considerable reduction incosts can be achieved by the easy windings.

FIG. 4 is in an unwinded view of the stator 3 and shows the coincidenceof alike current directions of windings 11 of adjacent stator teeth 7 inthe notches 9, wherein the winding of the stator teeth with a windingwire 19 is alternating. The symbols with respect to reference numeral 21show in turn the alternating induction directions of the serial windingand the thereby resulting single windings 11 with respect to tooth 7.FIG. 5 shows, with the stator corresponding to that in FIG. 4, the newwinding mode for stator 3 wherein a single winding wire 23 runs meander-or loop-like between the teeth. As shown, the winding is sinuouslyguided through the stator notches 9. This is continuously carried outring-like with the wire 23 over the circumference of the stator, untilthe desired filling factor of the stator notches is achieved. This‘rotating’ winding of the teeth is of course only possible with an evennumber of teeth of a stator. FIG. 6 is a three-dimensional view showingschematically the new winding mode also depicted in FIG. 5.

Advantages of the generator's winding in alternating direction asdescribed above:

-   -   It allows an easy, fast and automatic winding of the stator        teeth. This winding method is therefore very cost-efficient.    -   Except for the feed wires the whole copper of the windings is        effectively arranged at the stator tooth. Such winded electrical        machine therefore has a very high efficiency.    -   Due to the simple construction it is ideal for simple        applications, such as for a bicycle dynamo.    -   It also requires only two feed wires per stator disk.    -   This winding method can also be applied in multi-disk or unit        electrical machines as described below.

When applying an electrically excited rotor by using sliding contacts—inan embodiment—it is possible to similarly run and wind the rotor. In anembodiment not shown herein the rotor 1 can comprise, instead of thepermanent magnets 5 or in addition to the permanent magnets 5,excitation windings preferably winded around teeth of the rotor,correspondingly wound as the windings around the teeth 7 of the statorshown in FIG. 5. I.e. preferably a rotor winding is provided which—asthe stator winding 11 around the stator teeth 7—is winded around rotorteeth. In a further embodiment the rotor teeth can also comprisepermanent magnets or can be formed of permanent magnets. When combiningpermanent magnets with the rotor winding, the sequence of the windingdirection of the rotor winding corresponds to the sequence of thepolarities of the permanent magnets (alternating), so that, independency of the current direction and the current level, the magneticfield of the permanent magnets is increased or reduced by the rotorwinding. Preferably, both ends of the rotor windings are electricallyconnected to the supply voltage via uninterruptible sliding contacts (areversion of polarity is not necessary). Alternatively, one or bothelectrical connections can be effected via the bearing of the rotor.

In a further embodiment the generator/motor is formed as inner rotor, inwhich the windings can also be winded around inwardly projecting teethof the outer stators according to this scheme.

Winding in Alternating Direction in Even Notches:

Here the winding notches can be formed as straight slots, which againextremely simplifies the winding. FIG. 7A shows a cross-section of anembodiment of a stator 30, in which, deviating from the stator 3 as setforth above, radially broadening stator teeth 32 having intermediatestraight slots running in radial direction are provided instead of theT-formed stator teeth 7. FIG. 7B shows the stator 30 in perspectiveview. In radial direction the winding notches 34 substantially comprisethe same cross-section, which thus extremely simplifies the winding. Inan embodiment the notches 34 can be covered with a safety die in orderto secure the windings not to slide out of the slots 34.

When applying an electrically excited rotor by using sliding contacts,it is possible to similarly implement and wind the rotor.

Reduction of the Detent Torques by Angular Offset of Two Stator DisksArranged in a Row:

When assembling two or more of the above described generators in a rowand with an angular offset to each other, for example when using twounits with an offset of the half angle of the tooth angular spacing, thedetent torques almost compensate each other. Preferably the rotors haveno angular offset to each other, so that they are formed as a continuousor single rotor covering all stators or stator units. In a reverseembodiment the rotor magnets have an angular offset, while the statorsare assembled without angular offset. The electrical machine assembledin this way, comprising two or more generators with such an angularoffset, has a much smaller starting torque and can therefore startrotation much easier. This can be a big advantage when for example beingused in wind power stations. The windings on each stator are separateand are connected externally afterwards, for example via two or morerectifiers.

FIGS. 8 and 9 show the mechanical coupling of two individual generatorsas an example. A front and a back stator 30 a, 30 b have a mechanicaloffset of the half angle α, wherein the angle α is the angle between twoneighboring poles or stator teeth 32 a and 32 b. The center axis of astator tooth 32 a of the front stator 30 a thus coincides with notch 34b of the back stator 30 b. The rotors are coupled mechanically withoutangular offset, wherein here a continuous or one-price rotor 1 isprovided comprising magnets 5 which run along the axial depth of bothstators 30 a, b. When therefore in this arrangement the rotor poles 5 ofthe front electrical machine rest directly and cocentrical over thestator teeth 32 a of the front stator 30 a, then the rotor poles 5 restin this position cocentrical between the stator teeth 32 b of the backelectrical machine. Preferably both stators 30 a, b are rigidly coupledby a shaft with each other. Both electrical machines thereby form amechanical unit.

Advantages of a generator with the described angular offset:

-   -   The detent torques are reduced significantly.    -   The connection of two or more generators of this design in        combination with rectifying each of the generator voltages        enhances the quality of the generated direct current voltage and        the filtering with capacitors is further simplified.    -   A generator built in that way can also be used as electrical        motor (see the following description).

The dual generator, as described in FIGS. 8 and 9, having the angularoffset between two or more stators 30 a, b, can also be used asbrushless motor. Only an electrical circuit for electronic commutationis required.

Construction of a Brushless Direct Current Motor Using Angular Offset ofTwo or More Stators Mechanically Connected and Arranged in a RowStarting Form the Foregoing Described Embodiments.

The angular offset α of the stators 30 a, b from the magnet pole centerto the next magnet pole junction (that is half of the stator toothangular offset) results in time offset of the magnetic incidences.Therefore it is possible to use the resulting different magnetic powersto generate a rotation. For this, according to a scheme as described inthe following, the current directions or flows in the serial windings ofthe individual stators are controlled alternatingly and reversed using abridge circuit (see FIG. 11). This results in a rotation in the desireddirection, using the relative phasing of the winding excitation of thestator windings. When using two stators positioned in a row and eachwinded in series, this is basically comparable with the actuation withthe help of pedals of a bicycle, wherein the first pedal is pushed andthe second is pulled and vice versa. The stator windings push and pullthe magnet poles step by step into one direction. For this it isnecessary to detect the position of the rotor magnets by a sensor oralternatively by measuring the induction voltages in the statorwindings, generated when passing the magnet poles of the rotor.

The use of three or even a higher number of stators or stator diskspositioned in a row and having an angular offset as described before,results in even more connection possibilities of the stator windingslike star circuit, delta connection etc. . . .

FIG. 10A shows a linear-projected view showing in radial direction theway of winding of the twelve pole brushless motor (see also FIG. 9) usedhere for explanation. FIG. 10B shows the linear-projected representation(from axial direction). FIG. 10C shows the temporal control of thevoltage supplied to the winding wire 36 a, b and the position of thewinding teeth 32 b relative to the permanent magnets 5. The windingwires 36 a, b run in the notches 34 a, b around all stator teeth 32 a, bin an undulating way. Additionally the meander curling winding of thestators can be seen quite clearly. The teeth 32 a, b are numbered with 1to 12 for clarity. An angular offset α between the stators 30 a and 30 bis provided here too, as described above. The center of a tooth 32 a ofstator 30 a is on the same level as the notch 34 b of stator 30 b. Themagnets 5 of the rotor 1 comprise no angular offset to each other andcontinuously extend over both stators 30 a, b.

The diagram of the rotation in FIG. 10C shows the temporal behavior ofthe movement or position of the rotor magnets 5. Directly underneath,the phase of the voltage supplied to the winding wire 36 a of the stator30 a is depicted, and, further underneath, the phase of the voltagesupplied to the winding wire 36 b of the stator 30 b is shown (andcorrespondingly the current direction). The voltages shown in FIG. 10Care the voltages supplied to the windings 36 a, 36 b, as for examplesupplied by the transistors 48 shown in FIG. 11 to the windings 36 a, 36b. The result is a switching offset which corresponds to the angularoffset α of the stators. The duration of the pulses depends on thenumber of rotor magnets 5, the number of stator teeth 32 a, b and therotation speed.

FIG. 10B shows the winding when using the substantially rectangularnotches 34 a, b (see FIG. 7A), wherein the windings 36 a, b or W fill upthe notches completely as indicated. FIG. 10D shows the winding whenusing a stator 3 as shown in FIGS. 1A and 6.

A drive circuit for the motor is described below when referring to FIG.11.

Alternating Generator and Motor Operation Made with One and the SameElectrical Machine:

The above described design allows the operation of the electricalmachine as generator as well as motor. It is therefore convenient to usethis for example for vehicles as actuator as well as for energyrecovery. Required for this is an electronic switching mechanism whichfor example switches from motor to generator operation during pushoperation of the vehicle. The momentum thus transformed into electricalenergy, can be feed back to the power battery or to an electricitynetwork. Here the generator operation also has a braking effect whichcan be used for braking in a controlled manner.

FIG. 11 shows a block diagram of a motor drive unit 40 comprising acontrol unit for driving and energy recovery. If just a drive control isnecessary, then the arrangement can be simplified by omitting the energyrecovery section. The windings 36 a, b respectively both separatestators 30 a, b at the motor drive unit 40 are commutated electronically(FIGS. 9 and 10). For each stator disk 30 a, b a bridge circuit isprovided. The bridge circuits comprise each four power transistors orpower FETs 48, as shown here. The FETs receive their gate signals viagate lines 49 connected to a controller 42. The battery voltage (forexample when used as a vehicle motor) is applied to the terminals 50 a,b at the FETs 48.

As feedback for detecting the rotor position, respectively the positionof the magnet poles, two versions are shown. In one embodiment one ormore hall sensors 46 or optical sensors are assigned to the magnets 5,in order to detect the relative position of the rotor 1 relative to thestator 30 a or 30 b. The sensor signal is supplied to the controller 42via sensor lines 62. According to another embodiment the inductionvoltage at the winding wires 36 a, b is detected, which is particularlygenerated during the turning on and off operations. The inductionvoltage of both winding wires 36 a, b is supplied to the controller 42via the sense lines 60. In both embodiments of the position detecting,the start, the end, the speed as well as the polarity of each magnet canbe detected. In the controller 42 these signals are detected and used toadjust the respective switch timing and possibly to correct the phase.

At the controller 42 the desired rotation speed or power for the motoris set via the control lines 66. Preferably, the controller 42 isprovided with a pulse width control for adapting the energy of therectangular signals that are supplied to the FETs (see voltage phase atthe windings 36 a, b of the stators 30 a, b in FIG. 10C) according tothe requirements. The upper rectangular voltage signal shown in FIG. 10C(“phase stator 30 a/30 b at winding 36 a/36 b”) is superimposed by ahigher rectangular frequency, so that the voltage signal as shown inFIG. 10C below is supplied to the windings 36 a, b (“pulse width atwinding 36 a/36 b”—wherein the voltage signal shows the voltage asmeasured at the winding 36 a, 36 b applied voltage). This higherrectangular frequency is changed in its pulse width and therefore theenergy content is modified. The controller 42 can take this task in thecircuit version shown here.

In the lower part of FIG. 11 a possible extension for the recovery ofthe momentum is shown, the so called push or brake operation. In thepush or brake operation the driving energy is set to zero, thetransistors 48 of the bridge circuits for the stator excitation areturned off completely. The controller 42 switches or controls then thepower current lines to the bridge rectifiers 52 to be conductive andthus enables the flow of the induced current from the windings 36 a, bof the motor, which is now in generator operation. In generatoroperation the controller 42 controls a control logic 44 which in turncontrols TRIACs 58. Instead of the TRIACs also MOSFETs, thyristors orsimilar can be provided. The TRIACs 58 are arranged in the line betweenthe windings 36 a, b and the rectifiers 52 and separate the lines in thedrive mode (FETs 48 are switching). At the output of the rectifiers acapacitor 55 smoothes the voltage which is then supplied as directcurrent voltage to direct current voltage terminal 56, for example inorder to recharge the vehicle battery.

If then the drive mode is required again, these lines between thewindings 36 a, b and the rectifier 52 are switched off at an appropriatepoint of time (zero crossing) by turning off the TRIACs 58. Thetransistor bridge circuit including the FETs can now provide current tothe windings 36 a, b in a controlled manner.

FIG. 12 shows another embodiment of the generator/motor-arrangementshown in FIG. 11 which uses diodes D1 to D8 parallel to the FETs insteadof the rectifier arrangements 52. Elements of the circuit arrangementthat are the same to the ones shown in FIG. 11 have the same referencenumbers. The diodes D1 to D8 are connected inverse across the switchtransistors and also act as free-wheeling diodes as protection againstover-voltage pulses, for example at induction peaks during fastswitching operations. Per each four diodes a bridge rectifier isprovided at each of the stators (D1 to D4 for stator 36 a (motor windingW1) and D5 to D8 for stator 36 b (motor winding W2)). In embodimentshaving more stator windings, correspondingly four free-wheeling diodesare grouped for each (additional) stator windings as a bridge rectifier.

By means of the bridge rectifier arrangements D1-D4, D5-D8 the recoveryof the rotation energy is made possible using simple measures, as forexample in the so-called push or brake mode of the above motors and/oralso when using it as starter-generator for vehicles and similarapplications. It is to be noted here that by the electronic design ofthe power electronic in full bridges a bridge rectifier automaticallyresults due to the four free-wheeling diodes D1-D4, D5-D8, i.e. theseparate bridge rectifier arrangements 52 are not required here.

FIG. 13 shows a detailed portion of the generator/motor arrangement ofFIG. 12 and illustrates the mode of operation. Here a power part of astator commutation at the motor winding 36 a is shown. The bridgerectifier resulting from the free-wheeling diodes D1 to D4 is singledout by the bold lines and rectifies the AC current generated in thestator winding during the rotation of the rotor (for example in pushoperation). Therefore, the momentum is being recovered as chargingcurrent for a power source battery 70 or a starter battery,respectively.

The time diagram of FIG. 14 shows the voltage from the two statorsrectified with the diodes D1-D4 or D5-D8, wherein stator 1 correspondsto the stator winding 36 a and stator 2 corresponds to stator winding36. Due to the parallel connection of the bridge rectifiers D1-D4 andD5-D8 of the corresponding commutating bridges the rectified chargingcurrents/charging voltages combine with each other with a time offsetdue to the mechanical angular offset α of the stators (see 30 a and 30 bin FIG. 9) and therefore the offset of the windings 36 a and 36 b. Theresulting DC current voltage does not drop to zero and is easy to besmoothed. When in embodiments more than two stators being angularlyoffset to each other are used, the degree of smoothing of the combinedDC voltage (parallel connected stators 9) is even higher.

FIG. 15 shows a modification of the detail portion shown in FIG. 13. Theswitching transistors 48 remain turned off in charging operation. Due tothe inclusion of a control R into the diodes circuit it is now possibleto control the charging current. When the motor including the circuit ofFIG. 15 is for example used with a vehicle or to control the chargingcurrent in a feedback loop, the brake force can be changed via thecontroller R as required, such that the braking-energy is transformedinto a charging current as far as possible. The controller R alsocomprises for example a MOSFET power switch which is controlled by aseparate controller (not shown). This separate controller has thefunction of a charging controller for charging the power source oractuation battery 70 and/or of a brake force controller that controlsthe electrical energy taken from the motor in dependency of the desiredbraking power. The energy that is been taken for charging and/or brakingis controlled by the controller R using pulse width modulation of theswitching periods of the power switch for example.

In an embodiment not shown, the rotor comprises a rotor winding asalready described above and instead of the controller R of FIG. 15 acontroller is connected between the rotor windings voltage supply andthe rotor winding, such that the rotor magnetic field can be changedunder the control of the controller. The electrical energy extracted bythe stator windings is changeable thereby.

In an embodiment (not shown) of the generator/motor arrangement of FIGS.11 to 15 the arrangement only comprises the elements which are requiredfor the generator operation, that means the transistors 48, the sensor46, the controller 42 and the corresponding circuitry 49, 60, 62, 64 areomitted. In the case of FIG. 11 the control logic includes positiondetection (the signals of the sense lines 66 are supplied to an extendedlogic of the control logic 44) in order to control the thyristors 58.

Advantages of the above described DC motor:

-   -   The engine is brushless (except the rotor has excited winding,        for controlling the motor).    -   Due to the synchronous or asynchronous design (see below) and        the resulting high starting torque it runs clean and strong        (important for the actuation technique).    -   It is very simple and low-cost to be winded (meandering        winding).    -   It has a very compact design and therefore it is also very light        weight.    -   Apart from the feed lines the whole copper of the winding at the        stator tooth is effective, it also has very high efficiency        thereby.    -   When using a plurality of stator disks the detent torque is very        low.    -   Any number of stator disks is possible (at least two) in order        to increase the running smoothness.    -   It can be used as motor as well as generator for recovering the        kinetic energy, for example in the push or brake operation.        Asynchronous Operation of the Motor and/or the Generator

The motor comprising two stators 30 a and 30 b described above in FIGS.9 to 10 is also controllable as an asynchronous motor. This is generallytrue for motors having at least two of the above described stators orhaving winding teeth at the rotor and/or stator, wherein the windingsare winded according to the scheme shown in FIGS. 4, 5 and 10A. For theembodiment shown in FIG. 9 a phase comprising a higher basic frequencyis applied instead of the phase or voltage signals (“phase stator 30a/30 b at winding 36 a/36 b” shown in FIG. 10C). Therefore, in thewindings 30 a and 30 b a moving field or a field rotation running aheadis generated which actuates the rotor 1. The detection of the rotationsense of the motor respectively the relative position of the motor forsetting the selected sense of rotation is embodied as described inconnection with FIG. 11.

Also in the case of the phase signal having a higher ground frequencyfor the asynchronous operation the ground frequency itself can besuperimposed again by a pulse width modulated higher frequency(corresponding to the phase signal shown in FIG. 10C below) in order toimplement a power control. For such a control the circuit shown in FIG.11 can be applied, wherein the controller 42 and the FETs 48 arecorrespondingly adapted to higher frequencies.

Further Embodiments of the Electrical Machine

As an exception for the brushless embodiment when using permanentmagnets as rotor poles, there is the possibility of using anelectrically excited rotor. Then the poles are shaped as winded rotorteeth. The current is then supplied over sliding rings, especially foruse as vehicle dynamo or as controlled direct current generator.

In the above described generator/motor arrangement or in the meregenerator arrangement an electrically excited rotor alternately windedin series (replace the alternating permanent magnets) can be providedfor the generator operation as with the asynchronous powered motor.During or for the generator operation, charging current output by thebridge rectifier is supplied to the windings of the rotor by pulse widthmodulation, linear control or simple ON/OFF (control operation) andthereby is used for the rotor excitation.

In a further embodiment the number of the stator and runner polesdeviates from each other slightly and serves for reduction of detenttorques which is often observed when using the same number of poles.

When using the machine as motor, many different applications exist asthe system can be assembled in a modular way. For example the individualstators can be assembled in a line and with angular offset to eachother. The stators may be screwed or plugged and therefore the wholestator package can be expanded arbitrarily. When using identical statorsas non-variable part it reduces the manufacturing costs as the basicelements in different combinations (number/angular offset) result indifferent generator/motor types. A brushless motor assembled in this wayis electronically commutated.

In an embodiment (not shown) of the motor of FIGS. 10A to 15 the statoris electrically excited instead of the brushless version wherein thepoles of the rotor comprise permanent magnets. Hereby more controloptions for the motor are given.

Short Description of the Invention:

-   -   Brushless electrical machine of synchronous or asynchronous        design comprising a sequence of teeth arranged on the        circumference, which can be used as generator and, in an        embodiment having two or more stator stages, as generator or as        motor. An exception to the brushless embodiment is the        possibility of using a current excited rotor with conductive        windings instead of permanent magnets as rotor poles. The        current is supplied via sliding contacts.    -   In this machine it is advantageous to use the same or nearly the        same number of the teeth on the circumference of the stator as        the number of magnets or teeth (current excited rotor) on the        rotor, wherein the magnets of the rotor are alternately poled        around the circumference.    -   The field winding of the teeth are all connected in series        whereby the current in the stator winding can be supplied or        extracted through two connection lines.    -   Brushless electrical machine like before, wherein the number of        serial connected field windings is even.    -   Brushless electrical machine as described, wherein each stage of        the stator comprises an own field winding passed over the        circumference.    -   Brushless electrical machine as described, wherein the teeth of        the different stages of the stator can have a mechanical offset,        from one stage to the next around half the spacing between the        poles.    -   The center axis of a stator tooth of one stator stage coincides        with a gap or spacing between the teeth of another (second)        stator stage.    -   With more than two stator stages the teeth of the other stages        are preferably evenly distributed over the spacing angle between        two teeth of one stator stage.    -   Brushless electrical machine like before, wherein the magnets        and/or teeth of the rotors are aligned without angular offset        continuously over all stator stages.    -   Brushless electrical machine as described, wherein the brushless        commutating is implemented by an electronic circuit.    -   Brushless electrical machine as described, wherein the machine        is used as DC generator in combination with a rectifier as well        as it is used as a DC motor, for example for actuating a car and        the same time as generator for energy recovery or as brake (or        in combination for both purposes).    -   The brushless electrical machine as before can be used as DC        generator, as dynamo for vehicles, as direct current motor, as        starter for vehicles and as actuation motor for vehicles.

LIST OF REFERENCE NUMERALS

 1 rotor  3 stator  5 permanent magnet  7 winding tooth  9 groove/notch11 winding 12 AC voltage terminal 13 rectifier 15 capacitor 17 terminal19 winding 21 eddy 23 winding wire 30 stator 30a, b first, second stator32 stator tooth 32a, b winding tooth of first, second stator 34groove/notch 34a, b groove of first, second stator 36a, b winding offirst, second stator 40 motor drive unit 42 controller 44 controllogic/control circuit 46 sensor 48 transistor 49 gate lines 50a, bterminals 52 rectifier 54 capacitor 56 voltage terminal 58 thyristor 60sense line 62 sensor lines 64 mode line 66 control line 70 battery αoffset angle W, W1, W2 winding D1 . . . D8 diode U voltage t time

SEQUENCE LISTING

Not applicable

1. Electrical motor or generator, comprising: at least a first and asecond stator (30 a, 30 b), wherein the at least a first and a secondstator (30 a, 30 b) are arranged coaxial to each other and with anangular offset (α) to each other, a plurality of winding teeth (7, 32)arranged at the circumference of each of the stators (30 a, 30 b), thewinding teeth comprising windings and wherein all windings of eachstator are connected in series, a rotor (1), and a plurality ofpermanent magnets (5) arranged on the circumference of the rotor (1)wherein the permanent magnets (5) have alternating radial polarity poles(N,S).
 2. Motor or generator according to claim 1, which is designed inparticular as external rotor machine, wherein the rotor (1) surroundsthe at least a first and a second stator (30 a, 30 b), wherein the motoris a brushless machine.
 3. Motor or generator according to claim 1,wherein the angular offset (α) is 360°:(2×m), wherein m=number of teeth(32 a, b) of the first stator (30 a) or the rotor.
 4. Motor or generatoraccording to claim 1, comprising three or more stators, wherein the atleast three stators are coaxial and have an angular offset to eachother.
 5. Motor or generator according to claim 1, wherein at least twoof the stators (30 a, b) are provided as pre-manufactured modules. 6.Motor or generator according to claim 1, wherein a winding wire (23, 36a, 36 b) is passing in meander or loop form between the winding teeth(7, 32 a, 32 b).
 7. Motor or generator according to claim 1, wherein thenumber of the windings of a stator (3, 30 a, 30 b) is a multiple of 2and/or wherein the number of teeth (32 a, b) of the first and secondstator (30 a, b) is equal to or a multiple of 2, wherein n=1, 2, 3, . .. .
 8. Motor or generator according to claim 1, wherein the number ofthe permanent magnets (5) deviates from the number of winding teeth (7,32) of the rotors or stators (3, 30 a, 30 b), wherein in particular theratio of the number of permanent magnets (5) to the number of windingsor the ratio of the number of windings to the number of permanentmagnets is in the range between 1.05 to 1.3.
 9. Motor or generatoraccording to claim 1, wherein the cross-section of the grooves (34)between the winding teeth (32) does not substantially narrow from theinside to the outside, wherein in particular the cross section from theinside to the outside is constant or widens.
 10. Motor or generatoraccording to claim 1, comprising a rectifier arrangement (52; D1 . . .D4; D5 . . . D8) per phase winding (36 a, 36 b).
 11. Motor or generatoraccording to claim 10, comprising a generator control circuit (44) forcontrolling two rectifier power switches (58), in particular TRIACs orthyristors, per phase winding (36 a, 36 b), wherein the two rectifierpower switches (58) switch connection wires between each phase winding(36 a, 36 b) and the corresponding rectifier arrangement (52) under thecontrol of the generator control circuit (44).
 12. Motor or generatoraccording to claim 10, wherein each phase winding (36 a, 36 b) of themotor comprises four power switches (48) and the rectifier arrangement(D1 . . . D4; D5 . . . D8) of each phase winding is formed by fourrectifier elements, wherein each of the rectifier elements is connectedin parallel to one of the power switches.
 13. Motor or generatoraccording to claim 10, wherein a control unit (R) and/or a filterelement (54) is assigned to each of the rectifier arrangements (52; D1 .. . D4; D5 . . . D8).
 14. Electrical motor, comprising: at least a firstand a second stator (30 a, 30 b), wherein the at least a first and asecond stator (30 a, 30 b) arranged coaxial to each other and with anangular offset (α) to each other, a plurality of winding teeth (7, 32)arranged at the circumference of each of the stators (30 a, 30 b), thewinding teeth comprising windings and wherein all windings of a eachstator are connected in series, a rotor (1), wherein the rotor surroundsthe at least a first and a second stator, and a plurality of permanentmagnets (5) arranged on the circumference of the rotor (1), wherein thepermanent magnets (5) have alternating radial polarity poles (N,S). 15.Electrical motor or generator, comprising: at least a first and a secondstator (30 a, 30 b), wherein the at least a first and a second stator(30 a, 30 b) are arranged coaxial to each other and with an angularoffset (α) to each other, and wherein the at least a first and a secondstator (30 a, 30 b) are positioned axially adjacent each other, aplurality of winding teeth (7, 32) arranged at the circumference of eachof the stators (30 a, 30 b), the winding teeth comprising windings andwherein all windings of a each stator are connected in series, a rotor(1), wherein the rotor surrounds the at least a first and a secondstator, and a plurality of permanent magnets (5) arranged on thecircumference of the rotor (1), wherein the permanent magnets (5) havealternating radial polarity poles (N,S).